Method of manufacturing dispersion strengthened lead

ABSTRACT

A sheet of dispersion strengthened lead is made by rolling powder between rollers in known manner. The invention resides in the choice of parameters to give optimum results. The powder size has a maximum value of 250 microns with a mean between 50 and 80 microns, and not more than 10 percent of the powder by volume has a particle size below 10 microns.

United States Patent METHOD OF MANUFACTURING DISPERSION H STRENGTHENED LEAD 1 Claim, No Drawings US. Cl 264/111 Int. Cl t B221 3/18 Field of Search 264/1 1 l, 8,

[56] References Cited UNITED STATES PATENTS 1,938,876 12/1933 Takata 264/8 2,217,235 10/1940 Rieser 264/8 3,162,708 12/1964 Lund et al.. 264/111 3,484,305 12/1969 Rose et al. 264/12 Primary Examiner-Robert F. White Assistant Examiner.1. R. Hall Attorney-Holman, Glascock, Downing & Seebold ABSTRACT: A sheet of dispersion strengthened lead is made by rolling powder between rollers in known manner. The invention resides in the choice of parameters to give optimum results. The powder size has a maximum value of 250 microns with a mean between 50 and 80 microns, and not more than 10 percent of the powder by volume has a particle size below 10 microns.

METHOD OF MANUFACTURING DISPERSION STRENGTHENED LEAD This invention relates to the manufacture of dispersion strengthened lead.

The invention resides in a method of manufacturing a sheet of dispersion strengthened lead by rolling powder between rollers, characterized in that the maximum particle size of the powder is 250 microns, the mean particle size being between 50 and 80 microns and not more than 10 percent of the powder by volume having a particle size below 10 microns.

[t is found that if the above limits are adhered to, consistent results are obtained. The invention can be applied to the manufacture of plane sheets, or preformed sheets which are subsequently perforated so that the sheets constitute a grid suitable for use as a battery plate grid.

Preferably the oxide content of the powder lies between 0.4 and L5 percent by weight.

ln one example, dispersion strengthened lead powder was produced by spraying molten lead into a container, and controlling the proportion of oxide in the dispersion strengthened lead by spraying water into the molten lead spray to maintain the oxide content between 0.4 percent and 1.5 percent by weight. The spraying also ensures that the dispersion strengthened lead has less than 10 percent by volume of particles having a particle size below 10 microns. The powder was then classified by removing all particles above 250 microns, leaving a powder with a mean particle size between 50 and microns. The powder was then passed between rollers shaped to produce a sheet having an extended central portion of rectangular configuration with a thickness of 0.038 inches, with shorter rectangular ribs at each end of the central portion, the ribs having a thickness of 0.060 inches. The rolls were 8 inches in diameter, and a force of between 1 and 2 tons per inch width of strip was employed.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A method of making a sheet of dispersion strengthened lead by passing between rollers, to form said sheet, lead powder having an oxide content which lies between 0.4-1.5 percent by weight, said powder consisting of particles having a maximum size of 250 microns, a mean particle size of 50 -80 microns, and no more than 10 percent of the powder by volume having a particle size below 10 microns. 

